protected IAggregateEvaluator createEvaluator(IScalarEvaluator[] args) throws AlgebricksException {
final ArrayBackedValueStorage abvs = new ArrayBackedValueStorage();
final GrowableIntArray slots = new GrowableIntArray();
final ArrayBackedValueStorage dataArea = new ArrayBackedValueStorage();
final SequencePointable seq = (SequencePointable) SequencePointable.FACTORY.createPointable();
final VoidPointable p = (VoidPointable) VoidPointable.FACTORY.createPointable();
return new AbstractTaggedValueArgumentAggregateEvaluator(args) {
@Override
public void init() throws AlgebricksException {
abvs.reset();
slots.clear();
dataArea.reset();
}
@Override
public void finishPartial(IPointable result) throws AlgebricksException {
finish(result);
}
@Override
public void finish(IPointable result) throws AlgebricksException {
if (slots.getSize() != 1) {
try {
assembleResult(abvs, slots, dataArea);
} catch (SystemException e) {
throw new AlgebricksException(e);
}
result.set(abvs);
} else {
result.set(dataArea);
}
}
@Override
protected void step(TaggedValuePointable[] args) throws SystemException {
TaggedValuePointable tvp = args[0];
if (tvp.getTag() == ValueTag.SEQUENCE_TAG) {
tvp.getValue(seq);
int seqLen = seq.getEntryCount();
for (int j = 0; j < seqLen; ++j) {
seq.getEntry(j, p);
addItem(p);
}
} else {
addItem(tvp);
}
}
private void assembleResult(ArrayBackedValueStorage abvs, GrowableIntArray slots,
ArrayBackedValueStorage dataArea) throws SystemException {
try {
DataOutput out = abvs.getDataOutput();
out.write(ValueTag.SEQUENCE_TAG);
int size = slots.getSize();
out.writeInt(size);
if (size > 0) {
int[] slotArray = slots.getArray();
for (int i = 0; i < size; ++i) {
out.writeInt(slotArray[i]);
}
out.write(dataArea.getByteArray(), dataArea.getStartOffset(), dataArea.getLength());
}
} catch (IOException e) {
throw new SystemException(ErrorCode.SYSE0001, e);
}
}
private void addItem(final IPointable p) throws SystemException {
try {
dataArea.getDataOutput().write(p.getByteArray(), p.getStartOffset(), p.getLength());
slots.append(dataArea.getLength());
} catch (IOException e) {
throw new SystemException(ErrorCode.SYSE0001, e);
}
}